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Supra suddenly running lean


Josh42
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Hi all,

 

Currently out in Europe with the supra.

Since this morning, I noticed that the idle is rough, the AFR's at idle are 17+, on boost are normal and when cruising on the motorway at 60+ are normal (up to 60 is a lean condition)

 

There have also been another couple of symptoms.

 

- Car cuts out when rolling to a stop for junctions

 

- Stutters at low speeds

 

- boost controller is showing a vacuum of 6.9 at idle (normally around 9.9)

 

Have checked all vac lines and intake pipes for splits.

 

Running an AEMV2 and AEM wideband sensor

 

Help please?

 

 

 

Edited by Josh42 (see edit history)
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Sounds like something around your fuel pressure reg, check vac lines or leaks around that or inlet mani.

Edit, is the aem using closed loop feedback, may need new 02 sensor or cleaning.

 

Cheers Si, my initial thought was vac line but can't seem to find a leak - I'll get it smoke tested once back in the UK.

 

Unsure if the AEM is open or closed loop feedback, I'll remove the sensor and clean it now regardless.

 

Thanks again!

 

 

 

 

 

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  • 1 month later...
Is the aem v2 external map sensor ? Is the ecu faulty?

 

- - - Updated - - -

 

What logging does it offer? Any info from that?

 

Hi Andy,

 

Thanks for the response.

 

The map sensor is external, yes. It's a 3bar AEM item.

 

I'm just downloading AEM tuner now, but if I'm honest, I'm unsure as to what i should be looking for

 

 

 

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It sounds like it's got an air leak on the engine side of the throttle valve. Slowly pour cold water over all the intake side with engine warm and idling, round injectors, gaskets, hoses. if engine idle changes stop immediately to avoid a big leak (which it DOESN'T sound like...) from sucking a load of water in. Investigate that region. RTV can be your friend for emergency vac leak repairs.

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Have you got an external fuel pressure regulator? Might be worth checking if it's still holding pressure that it was set at. Check with vacuum attatched/detatched and post what figures you are getting.

 

If you had a vac leak then it shouldn't make you run leaner, you should be running richer. For instance if you are normally running at -9 vacuum , but are now running -6 then you would be referencing a fuel cell higher up in the table which presumably would have more fuel rather than less as it's closer to 100 kpa, unless your tune is setup differently?. If you can post your logs then I can confirm the above.

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Unfortunately it would appear I've lost the coms cable for the AEM so I'll grab one in the morning and post the logs.

 

Thank you all for your input thus far, it is very much appreciated.

 

Chris, do you think that's a better method than smoke testing? The smoke test highlighted nothing other than a leak on my exhausts centre section.

 

If so, I'll try that in the morning too.

 

Thanks again

 

 

 

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Have you got an external fuel pressure regulator? Might be worth checking if it's still holding pressure that it was set at. Check with vacuum attatched/detatched and post what figures you are getting.

 

If you had a vac leak then it shouldn't make you run leaner, you should be running richer. For instance if you are normally running at -9 vacuum , but are now running -6 then you would be referencing a fuel cell higher up in the table which presumably would have more fuel rather than less as it's closer to 100 kpa, unless your tune is setup differently?. If you can post your logs then I can confirm the above.

 

Hi Mike,

 

Thanks for the detailed response.

 

I'm running the stock FPR mate, I could swap it out for a spare I have to eliminate that also.

 

I'll post the logs up tomorrow once I have the cable.

 

Cheers,

Josh

 

 

 

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Hi Mike,

 

Thanks for the detailed response.

 

I'm running the stock FPR mate, I could swap it out for a spare I have to eliminate that also.

 

I'll post the logs up tomorrow once I have the cable.

 

Cheers,

Josh

 

 

/QUOTE]

 

Hmm, I haven't seen a stock FPR die yet in my experiences, it's normally the aftermarket ones that can throw a wobbly.

 

On the assumption that the stock FPR hasnt died, then maybe take the fuel hanger out of the fuel tank and make sure the pump has not come out of the hanger, and the fuel line used between the hanger and pump isn't damaged in anyway. Whilst you're there, check that whatever is powering your pump is still giving proper battery voltage on idle/boost etc.

 

If that's all ok, then I would suggest getting a fuel presssure tester on just to be 100% sure that the fuel pressure is as expected using your setup.

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Not very successful day...

 

Unfortunately, my tuner has password protected the ECU, which has prevented me from data logging.

 

I did swap a friends inlet setup on (throttle body and y piece) to no avail.

 

I tried the water test as suggested by CW, but nothing came to light.

 

The only thing that has highlighted itself is that the pigtail harnesses for my injectors are pants. Even when wiggling them lightly, the car begins to misfire and lean out. My first port of call is to hardwire these in.

 

Also changed the exhaust gaskets, I would say they are long overdue....

 

image

 

 

 

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Not very successful day...

 

Unfortunately, my tuner has password protected the ECU, which has prevented me from data logging.

 

I did swap a friends inlet setup on (throttle body and y piece) to no avail.

 

I tried the water test as suggested by CW, but nothing came to light.

 

The only thing that has highlighted itself is that the pigtail harnesses for my injectors are pants. Even when wiggling them lightly, the car begins to misfire and lean out. My first port of call is to hardwire these in.

 

Also changed the exhaust gaskets, I would say they are long overdue....

 

https://uploads.tapatalk-cdn.com/20170820/95f8df8de6a6a723a6cedb5926810674.jpg

 

 

/QUOTE]

 

Bummer. Well as you paid x amount for tuning it should be your right to access YOUR ecu to at least get logging enabled. Maybe worth giving them a call to ask for the password, logging is a pretty fundamental part of having a standalone.

 

Hopefully it's just the pigtails though, good luck

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Bummer. Well as you paid x amount for tuning it should be your right to access YOUR ecu to at least get logging enabled. Maybe worth giving them a call to ask for the password, logging is a pretty fundamental part of having a standalone.

 

Hopefully it's just the pigtails though, good luck

 

No joy, they are flatly refusing to provide the password, claiming intellectual property.

 

 

 

 

 

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Always, ALWAYS, *ALWAYS* get a written agreement that a mapper is going to furnish you with the map before having mapping done. I see this all the time.

 

As an aside DTA had a disgruntled employee a few years back (at least I think it was a disgruntled employee...) who released the back door password that unlocked all DTA ecu's....

 

You know, the back door that didn't exist.... ;) Mucho aggravation and legal huffing and puffing...

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No joy, they are flatly refusing to provide the password, claiming intellectual property.

 

 

 

 

/QUOTE]

 

Lol that's horseshit.

 

I could understand if we were talking about 2017 F1 ecu secrets, but it's a 2jz. Not like that hasn't been mapped a million times already.

 

If they wanna play tough then just get them to remote onto your laptop and enable logging, that way they aren't sharing the password.

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